Fermi level shift in La1−xSrxMO3 (M=Mn, Fe, Co, and Ni) probed by Schottky-like heteroepitaxial junctions with SrTi0.99Nb0.01O3

The authors have studied electrical properties of perovskite heteroepitaxial junctions consisting of transition metal oxides La1−xSrxMO3 (LSMO: M=Mn, Fe, Co, and Ni) and an n-type semiconductor SrTi0.99Nb0.01O3 (Nb:STO). The junctions showed rectifying current-voltage characteristics that could be analyzed by taking into account a Schottky-like barrier formed in the Nb:STO at the interfaces. As the doping level x is increased, the Schottky barrier height and built-in potential increase as ∼x (eV), indicating the downward shift of the Fermi level position in the LSMO. The Fermi level position in the LSMO with the same doping level x tends to be deepened with increasing the atomic number of M, in the order of Mn, Fe, Co, and Ni.